Efficacy of intentional permanent atrial pacing in the long-term management of congenital long QT syndrome.

BACKGROUND: Unfortunately, some patients with long QT syndrome (LQTS) experience breakthrough cardiac events (BCEs) despite maximal therapy. Small studies have shown that refractory LQTS cases may benefit from intentional permanent atrial pacing (IPAP). As such, we sought to determine the genotype-specific utilization and efficacy of IPAP in a single-center LQTS registry. METHODS AND RESULTS: In this retrospective study, electronic medical records from 1065 patients diagnosed with LQTS were used to identify individuals that received IPAP. Pre- and post-IPAP heart rate, heart rate-corrected QT (QTc) values, annual BCE rate, and IPAP-related complications were compared between genotypes. BCEs were defined as LQTS-associated syncope/seizures, sustained ventricular arrhythmia (VA)-terminating ICD therapies, and sudden cardiac arrest/death. Overall, 52 out of 1065 LQTS patients received adjunctive IPAP therapy (77% female; median age 18.5 [interquartile range, 1-35.5] years; 73% with prior VA). Over an average IPAP follow-up of 121 ± 82 months, the average heart rate increased from 65.8 ± 20.4 bpm to 78.9 ± 17.1 bpm; (p < .01) and the average QTc decreased from 533.4 ± 66.6 to 488.3 ± 52.4 ms; (p < .01). The mean BCE rate dropped from 0.88 to 0.19 per patient-year (p = .01), driven by a marked decrease in the LQT2 cohort (1.01 BCE/year to 0.02 BCE/year; p = .003). No serious IPAP-related complications were observed. CONCLUSION: In high-risk LQTS patients, namely those with recalcitrant LQT2, IPAP appears to be a safe and efficacious adjunct therapy. The beneficial effects of IPAP may stem from attenuating the QTc and circumventing a pause-dependent trigger. Whether IPAP might obviate the need for an ICD in some instances warrants further study.

Purkinje system hyperexcitability and ventricular arrhythmia risk in type 3 long QT syndrome.

BACKGROUND: Gain-of-function variants in the SCN5A-encoded Nav1.5 sodium channel cause type 3 long QT syndrome (LQT3) and multifocal ectopic Purkinje-related premature contractions. Although the Purkinje system is uniquely sensitive to the action potential-prolonging effects of LQT3-causative variants, the existence of additional Purkinje phenotype(s) in LQT3 is unknown. OBJECTIVE: The purpose of this study was to determine the prevalence and clinical implications of frequent fascicular/Purkinje-related premature ventricular contractions (PVCs) and short-coupled ventricular arrhythmias (VAs), suggestive of Purkinje system hyperexcitability (PSH), in a single-center LQT3 cohort. METHODS: A retrospective analysis of 177 SCN5A-positive patients was performed to identify individuals with a LQT3 phenotype. Available electrocardiographic, electrophysiology study, device, and genetic data from 91 individuals with LQT3 were reviewed for evidence of presumed fascicular PVCs and short-coupled VAs. The relationship between PSH and ventricular fibrillation events was assessed by Kaplan-Meier and Cox regression analyses. RESULTS: Overall, 30 of 91 patients with LQT3 (33%) exhibited evidence of presumed PSH (fascicular PVCs 30 of 30 [100%]; short-coupled VAs 17 of 30 [56%]). Kaplan-Meier and Cox regression analyses demonstrated an increased risk of ventricular fibrillation events in individuals with LQT3 and PSH (log-rank, P < .03; hazard ratio 3.95; 95% confidence interval 1.15-15.7; P = .03). Interestingly, variants in the voltage-sensing domain regions of Nav1.5 were more frequently observed in patients with LQT3 and PSH than those without (19 of 30 [63%] vs 9 of 61 [15%]; P < .0001). CONCLUSION: This study demonstrates that a discernible Purkinje phenotype is present in one-third of LQT3 cases and increases the risk of potentially lethal VAs. Further study is needed to determine whether a distinct cellular electrophysiology phenotype underlies this phenomenon.

Total and Cause-Specific Mortality After Percutaneous Coronary Intervention: Observations From the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease Registry.

BACKGROUND: Patients undergoing percutaneous coronary intervention (PCI) are increasingly older and have a higher comorbidity burden. This study evaluated trends in 30-day, 1-year, and 2-year total and cause-specific mortality using a large, contemporary cohort of patients who underwent PCI in Alberta, Canada. METHODS: We used the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry to identify patients aged ≥ 20 years who underwent PCI between 2005 and 2013. All patients were followed until death or being censored by August 2016. Cause of death was from the Vital Statistics database and classified as cardiac or noncardiac. Multivariable logistic regression was used to calculate predicted mortality at 30 days, 1 year, and 2 years post-PCI. RESULTS: Of the 35,602 patients who underwent PCI, 5284 (14.8%) had died. Mean (standard deviation) follow-up was 74.9 (35.1) months. Over the study period, patients were older and more likely to undergo PCI for an acute coronary syndrome indication. Thirty-day (2005: 1.3%; 2013: 3.2%; P < 0.001), 1-year (2005: 2.7%; 2013: 5.7%; P < 0.001), and 2-year (2005: 4.5%; 2013: 7.5%; P < 0.001) predicted mortality after PCI increased over the study period. Cardiac cause of death dominated in the short-term, but the proportion of noncardiac deaths increased as time from PCI to death increased (30 days = 11.5%, 1 year = 31.5%, 2 years = 39.6%; P < 0.001). CONCLUSIONS: In this population-based study, we found all-cause mortality at 30 days, 1 year, and 2 years after PCI increased over time. Cardiac causes of death dominate in the short-term after PCI; however, noncardiac cause becomes a major driver of mortality in the long-term.

CONTEXTE: Les patients devant subir une intervention coronarienne percutanée (ICP) sont de plus en plus âgés et subissent un fardeau accru de comorbidités. La présente étude a évalué les tendances de la mortalité totale et due à une cause particulière à 30 jours, 1 an et 2 ans, au sein d'une vaste cohorte contemporaine de patients ayant subi une ICP en Alberta, au Canada. MÉTHODOLOGIE: Nous avons utilisé le registre APPROACH (Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease) pour recenser les patients âgés de 20 ans ou plus qui avaient subi une ICP entre 2005 et 2013. Tous les patients ont fait l'objet d'un suivi jusqu'au décès ou à la censure des données en août 2016. La cause du décès était issue de la Base de données sur l'état civil et classée comme étant d'origine cardiaque ou non cardiaque. On a eu recours à un modèle de régression logistique multivarié pour calculer la mortalité prédite 30 jours, 1 an et 2 ans après l'ICP. RÉSULTATS: Sur les 35 602 patients ayant subi une ICP, 5 284 (14,8 %) étaient décédés. La durée moyenne de suivi (écart type) était de 74,9 (35,1) mois. Au cours de la période de l'étude, les patients étaient plus âgés et plus susceptibles de subir une ICP pour une indication de syndrome coronarien aigu. On observe une augmentation de la mortalité prédite après l'ICP au cours de la période de l'étude selon les taux suivants : à trente jours (2005 : 1,3 %; 2013 : 3,2 %; p < 0,001), à 1 an (2005 : 2,7 %; 2013 : 5,7 %; p < 0,001) et à 2 ans (2005 : 4,5 %; 2013 : 7,5 %; p < 0,001). Les causes cardiaques de décès dominaient à court terme, mais la proportion de décès d'origine non cardiaque augmentait avec le temps au fur et à mesure de l'allongement de l'intervalle entre la date de l'ICP et le décès (30 jours = 11,5 %, 1 an = 31,5 %, 2 ans = 39,6 %; p < 0,001). CONCLUSIONS: Dans cette étude de population, nous avons trouvé que la mortalité toutes causes confondues à 30 jours, 1 an et 2 ans après une ICP augmente au fil du temps. Les causes cardiaques de décès dominent peu de temps après l'ICP, tandis que les causes non cardiaques jouent un rôle déterminant dans la mortalité à long terme.

Subclinical Atrial Fibrillation in Older Patients.

BACKGROUND: Long-term continuous electrocardiographic monitoring shows a substantial prevalence of asymptomatic, subclinical atrial fibrillation (SCAF) in patients with pacemakers and patients with cryptogenic stroke. Whether SCAF is also common in other patients without these conditions is unknown. METHODS: We implanted subcutaneous electrocardiographic monitors (St. Jude CONFIRM-AF) in patients ≥65 years of age attending cardiovascular or neurology outpatient clinics if they had no history of atrial fibrillation but had any of the following: CHA2DS2-VASc score of ≥2, sleep apnea, or body mass index >30 kg/m2. Eligibility also required either left atrial enlargement (≥4.4 cm or volume ≥58 mL) or increased (≥290 pg/mL) serum NT-proBNP (N-terminal pro-B-type natriuretic peptide). Patients were monitored for SCAF lasting ≥5 minutes. RESULTS: Two hundred fifty-six patients were followed up for 16.3±3.8 months. Baseline age was 74±6 years; mean CHA2DS2-VASc score was 4.1±1.4; left atrial diameter averaged 4.7±0.8 cm; and 48% had a prior stroke, transient ischemic attack, or systemic embolism. SCAF ≥5 minutes was detected in 90 patients (detection rate, 34.4%/y; 95% confidence interval [CI], 27.7-42.3). Baseline predictors of SCAF were increased age (hazard ratio [HR] per decade, 1.55; 95% CI, 1.11-2.15), left atrial dimension (HR per centimeter diameter, 1.43; 95% CI, 1.09-1.86), and blood pressure (HR per 10 mm Hg, 0.87; 95% CI, 0.78-0.98), but not prior stroke. The rate of occurrence of SCAF in those with a history of stroke, systemic embolism, or transient ischemic attack was 39.4%/y versus 30.3%/y without (P=0.32). The cumulative SCAF detection rate was higher (51.9%/y) in those with left atrial volume above the median value of 73.5 mL. CONCLUSIONS: SCAF is frequently detected by continuous electrocardiographic monitoring in older patients without a history of atrial fibrillation who are attending outpatient cardiology and neurology clinics. Its clinical significance is unclear. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01694394.

Limitations of Condensed Teaching Strategies to Develop Hand-Held Cardiac Ultrasonography Skills in Internal Medicine Residents.

Advances in ultrasonographic technology have allowed for hand-held cardiac ultrasonography (HHCU) units that fit into a physician's laboratory coat. Recently, studies to educate internal medicine residents have shown promise. The optimal duration and methodology for teaching HHCU skills has not been established. Over a 1-year period, internal medicine residents were recruited during their cardiology ward rotation into a single-centre nonblinded randomized trial. The 2 condensed teaching strategies were (1) a conventional ward-based program and (2) a technology-driven simulation-based strategy. Outcomes were evaluated by (1) an objective structured clinical examination (OSCE) to evaluate interpretation ability (assessing both type I and type II error rates) and (2) demonstration of HHCU skills graded by 2 level III echocardiographers. Twenty-four internal medicine residents were randomized. After teaching, the conventional teaching group had a significant absolute increase in the ability to make a singular correct diagnosis (20%; P < 0.001). In the technology arm, making a singular correct diagnosis increased 24% from baseline (P = 0.001). Interpretation skill was not significantly different between groups. The false-positive rate increased by an absolute 14% and 17% in the conventional and technology groups, respectively (P = 0.079 and P = 0.008). Our findings suggest that HHCU interpretation skills improve after either a conventional ward-based or a technology-driven approach. However, our study emphasizes the important limitations of both teaching programs, because we detected a trend toward an increase in the false-positive rate after both approaches. This suggests that a short duration of training may not be sufficient for HHCU to be performed in a safe manner.

High prevalence of modifiable stroke risk factors identified in a pharmacy-based screening programme.

BACKGROUND: Population-based screening for atrial fibrillation (AF) is a promising public health strategy to prevent stroke. However, none of the published reports have evaluated comprehensive screening for additional stroke risk factors such as hypertension and diabetes in a pharmacy setting. METHODS: The Program for the Identification of 'Actionable' Atrial Fibrillation in the Pharmacy Setting (PIAAF-Pharmacy) screened individuals aged ≥65 years, attending community pharmacies in Canada, who were not receiving oral anticoagulation (OAC). Participants were screened for AF using a hand-held ECG device, had blood pressure (BP) measured, and diabetes risk estimated using the Canadian Diabetes Risk Assessment Questionnaire (CANRISK) questionnaire. 'Actionable' AF was defined as unrecognised or undertreated AF. A 6-week follow-up visit with the family physician was suggested for participants with 'actionable' AF and a scheduled 3-month visit occurred at an AF clinic. RESULTS: During 6 months, 1145 participants were screened at 30 pharmacies. 'Actionable' AF was identified in 2.5% (95% CI 1.7 to 3.6; n=29); of these, 96% were newly diagnosed. Participants with 'actionable AF' had a mean age of 77.2±6.8 years, 58.6% were male and 93.1% had a CHA2DS2-VASc score ≥2. A BP>140/90 was found in 54.9% (616/1122) of participants and 44.4% (214/492) were found to be at high risk of diabetes. At 3 months, only 17% of participants were started on OAC, 50% had improved BP and 71% had confirmatory diabetes testing. CONCLUSIONS: Integrated stroke screening identifies a high prevalence of individuals who could benefit from stroke prevention therapies but must be coupled with a defined care pathway.

Resident Physicians Choices of Anticoagulation for Stroke Prevention in Patients With Nonvalvular Atrial Fibrillation.

Atrial fibrillation (AF) is a common cardiac arrhythmia and is associated with an increased risk of ischemic stroke. The aim of this study was to identify practice patterns of Canadian resident physicians pertaining to stroke prevention in nonvalvular AF according to the Canadian Cardiovascular Society guidelines. A Web-based survey consisting of 16 multiple-choice questions was distributed to 11 academic centres. Questions involved identification of risks of stroke, bleeding, and selection of appropriate therapy in clinical scenarios that involve a patient with AF with a Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack (CHADS2) score of 3 and no absolute contraindications to anticoagulation. There were 1014 total respondents, of whom 570 were internal, 247 family, 137 emergency medicine, and 60 adult cardiology residents. For a patient with a new diagnosis of AF, warfarin was chosen by 80.3%, novel oral anticoagulants (NOACs) by 60.3%, and acetylsalicylic acid (ASA) by 7.2% of residents. To a patient with a history of gastrointestinal bleed during ASA treatment, warfarin was recommended by 75.1%, NOACs by 36.1%, ASA by 12.1%, and 4% were unsure. For a patient with a history of an intracranial bleed, warfarin was recommended by 38.8%, NOACs by 23%, ASA by 24.8%, and 18.2% were unsure. For a patient taking warfarin who had a labile international normalized ratio, 89% would switch to a NOAC and 29.5% would continue warfarin. This study revealed that, across a wide sampling of disciplines and centres, resident physician choices of anticoagulation in nonvalvular AF differ significantly from contemporary Canadian Cardiovascular Society guidelines.

Pseudo-ventricular tachycardia mimicking malignant arrhythmia in a patient with rapid atrial fibrillation.

Artifacts can simulate arrhythmias such as atrial flutter, atrial fibrillation, and ventricular tachycardia. A case of pseudo-ventricular tachycardia is outlined in a patient with newly diagnosed atrial fibrillation, which made the diagnosis a special challenge. Characteristic signs of pseudo-ventricular tachycardia are described. This case reinforces the importance of recognizing artifacts to avoid unnecessary interventions, especially in the telemetry and critical care units.

Prolonged P-wave duration is associated with atrial fibrillation recurrence after successful pulmonary vein isolation for paroxysmal atrial fibrillation.

UNLABELLED: Pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) is successful in ∼70-80 % after repeated procedures. This suggests a subgroup of PAF patients where electrical abnormalities outside the pulmonary veins are important. Prolonged P-wave duration (PWD), a marker of atrial remodelling, may identify this subgroup. This study's aim was to assess the association of PWD on standard 12 lead ECG with AF recurrence post PVI. METHODS: Retrospectively, ECGs were blindly analysed on PVI patients from August 2007-August 2011; patients with persistent AF, mitral valve disease, undergoing redo procedures or no sinus rhythm (SR) ECG within 1 year of PVI were excluded. ECGs were directly uploaded at 300 dpi, amplified ×10, and then PWD measured in all leads. Prolonged PWD was as priori defined as maximum PWD ≥ 140 ms. RESULTS: The selective cohort consisted of 100 patients out of a total of 170 PVI: age 58 ± 11 years, 72 % male, LVEF 62 ± 9 %, 18 % ischaemic heart disease and 13 % diabetic. Thirty-five had prolonged PWD, which was associated with greater AF recurrence rates compared to those without prolonged PWD (63 vs. 38 %, p < 0.05). Similarly, AF recurrence was associated with greater maximum PWD (139 ± 17 vs. 129 ± 14, p < 0.01), P-wave dispersion (58 ± 21 vs. 49 ± 15, p < 0.01), left atrium (LA) dimension (41 ± 6 vs. 38 ± 5, p < 0.05) and LA volumes (40 ± 14 vs. 34 ± 11, p < 0.05) compared to those who remained in SR. None of these variables were independent predictors of AF recurrence by multivariate analysis. CONCLUSION: The presence of pre-existent prolonged PWD is associated with a higher risk of AF recurrence post PVI for paroxysmal AF.

The velvet myocardium: potential harbinger of death in acute myocarditis?

A case of fulminant myocarditis in a young man is described. Bedside hand-held focused cardiac ultrasound demonstrated severe systolic dysfunction with hypertrophied myocardium. Echocardiogram showed a speckled texture of the myocardium and a "velvet-like" appearance. Unfortunately, the patient developed cardiogenic shock and despite aggressive management, he died. The autopsy showed multifocal lymphohistiocytic infiltration and myocyte injury. We propose that the "velvet" myocardial ultrasonic appearance with ventricular hypertrophy is an indicator of rapid clinical demise.

Atrioventricular Nodal Re-entry Tachycardia in Identical Twins: A Case Report and Literature Review.

This report details the case of 17 year old identical twins who both presented with paroxysmal supraventricular tachycardia (PSVT). Electrophysiological studies revealed atrioventricular nodal reentry tachycardia (AVNRT) in both twins. Successful but technically challenging slow pathway ablation was performed in both twins. This is the first reported case of confirmed AVNRT in identical twins which adds strong evidence to heritability of the dual AV node physiology and AVNRT. A review of the current literature regarding PSVT in monozygotic twins is provided.